Interlayer environment engineered MXene: Pre-intercalated Zn^(2+)ions as intercalants renders the modulated Li storage

The intercalation of foreign species into MXene, as an approach of tuning the interlayer environment, is employed to improve electrochemical ion storage behaviors. Herein, to understand the effect of confined ions by the MXene layers on the performance of electrochemical energy storage, Zn^(2+) ions were employed to intercalate into MXene via an electrochemical technique. Zn^(2+) ions induced a shrink of the adjacent MXene layers. Meaningfully, a higher capacity of lithium ion storage was obtained after Zn^(2+) preintercalation. In order to explore the roles of the intercalated Zn^(2+) ions, the structural evolution, and the electronic migration among Zn, Ti and the surface termination were investigated to trace the origination of the higher Li^(+) storage capacity. The pre-intercalated Zn^(2+) ions lost electrons, meanwhile Ti of MXene obtained electrons. Moreover, a low-F surface functional groups was achieved. Contrary to the first shrink, after 200 cycles, a larger interlayer distance was monitored, this can accelerate the ion transport and offer a larger expansile space for lithium storage. This may offer a guidance to understand the roles of the confined ion by two-dimensional(2D) layered materials.

Layered Potassium Titanium Niobate/Reduced Graphene Oxide Nanocomposite as a Potassium‑Ion Battery Anode

With graphite currently leading as the most viable anode for potassium-ion batteries(KIBs),other materials have been left relatively underexamined.Transition metal oxides are among these,with many positive attributes such as synthetic maturity,longterm cycling stability and fast redox kinetics.Therefore,to address this research deficiency we report herein a layered potassium titanium niobate KTiNbO5(KTNO)and its rGO nanocomposite(KTNO/rGO)synthesised via solvothermal methods as a high-performance anode for KIBs.Through effective distribution across the electrically conductive rGO,the electrochemical performance of the KTNO nanoparticles was enhanced.The potassium storage performance of the KTNO/rGO was demonstrated by its first charge capacity of 128.1 mAh g^(−1) and reversible capacity of 97.5 mAh g^(−1) after 500 cycles at 20 mA g^(−1),retaining 76.1%of the initial capacity,with an exceptional rate performance of 54.2 mAh g^(−1)at 1 A g^(−1).Furthermore,to investigate the attributes of KTNO in-situ XRD was performed,indicating a low-strain material.Ex-situ X-ray photoelectron spectra further investigated the mechanism of charge storage,with the titanium showing greater redox reversibility than the niobium.This work suggests this lowstrain nature is a highly advantageous property and well worth regarding KTNO as a promising anode for future high-performance KIBs.

Charting the course to solid-state dual-ion batteries

An electrolyte destined for use in a dual-ion battery(DIB)must be stable at the inherently high potential required for anion intercalation in the graphite electrode,while also protecting the Al current collector from anodic dissolution.A higher salt concentration is needed in the electrolyte,in comparison to typical battery electrolytes,to maximize energy density,while ensuring acceptable ionic conductivity and operational safety.In recent years,studies have demonstrated that highly concentrated organic electrolytes,ionic liquids,gel polymer electrolytes(GPEs),ionogels,and water-in-salt electrolytes can potentially be used in DIBs.GPEs can help reduce the use of solvents and thus lead to a substantial change in the Coulombic efficiency,energy density,and long-term cycle life of DIBs.Furthermore,GPEs are suited to manufacture compact DIB designs without separators by virtue of their mechanical strength and electrical performance.In this review,we highlight the latest advances in the application of different electrolytes in DIBs,with particular emphasis on GPEs.

Structural engineering of potassium vanadate cathode by pre-intercalated Mg_(2+) for high-performance and durable rechargeable aqueous zinc-ion batteries

Aqueous zinc(Zn)-ion batteries(AZIBs)have the potential to be used in massive energy storage owing to their low cost,eco-friendliness,safety,and good energy density.Significant research has been focused on enhancing the performance of AZIBs,but challenges persist.Vanadium-based oxides,known for their large interlayer spacing,are promising cathode materials.In this report,we synthesize Mg^(2+)-intercalated potassium vanadate(KVO)(MgKVO)via a single-step hydrothermal method and achieve a 12.2°Ainterlayer spacing.Mg^(2+) intercalation enhances the KVO performance,providing wide channels for Zn^(2+),which results in high capacity and ion diffusion.The combined action of K^(+) and Mg^(2+) intercalation enhances the electrical conductivity of MgKVO.This structural design endows MgKVO with excellent electrochemical performance.The AZIB with the MgKVO cathode delivers a high capacity of 457 mAh g^(-1) at 0.5 A g^(-1),excellent rate performance of 298 mAh g^(-1) at 5 A g^(-1),and outstanding cycling stability of 102%over 1300 cycles at 3 A g^(-1).Additionally,pseudocapacitance analysis reveals the high capacitance contribution and Zn^(2+)diffusion coefficient of MgKVO.Notably,ex-situ X-ray diffraction,X-ray photoelectron spectroscopy,and Raman analyses further demonstrate the Zn^(2+)insertion/extraction and Zn-ion storage mechanisms that occurred during cycling in the battery system.This study provides new insights into the intercalation of dual cations in vanadium oxides and offers new solutions for designing cathodes for high-capacity AZIBs.

F-doped orthorhombic Nb_(2)O_(5) exposed with 97% (100) facet for fast reversible Liþ-Intercalation

Orthorhombic Nb_(2)O_(5)(T-Nb_(2)O_(5))is attractive for fast-charging Li-ion batteries,but it is still hard to realize rapid charge transfer kinetics for Li-ion storage.Herein,F-doped T-Nb_(2)O_(5) microflowers(F-Nb_(2)O_(5))are rationally synthesized through topotactic conversion.Specifically,F-Nb_(2)O_(5) are assembled by single-crystal nanoflakes with nearly 97%exposed(100)facet,which maximizes the exposure of the feasible Li^(+)transport pathways along loosely packed 4g atomic layers to the electrolytes,thus effectively enhancing the Li^(+)-intercalation performance.Besides,the band gap of F-Nb_(2)O_(5) is reduced to 2.87 eV due to the doping of F atoms,leading to enhanced electrical conductivity.The synergetic effects between tailored exposed crystal facets,F-doping,and ultrathin building blocks,speed up the Li^(+)/electron transfer kinetics and improve the pseudocapacitive properties of F-Nb_(2)O_(5).Therefore,F-Nb_(2)O_(5) exhibit superior rate capability(210.8 and 164.9 mAh g^(-1) at 1 and 10 C,respectively)and good long-term 10 C cycling performance(132.7 mAh g^(-1) after 1500 cycles).

Modulating charge separation and transfer for high-performance photoelectrodes via built-in electric field

Constructing a built-in electric field has emerged as a key strategy for enhancing charge separation and transfer,thereby improving photoelectrochemical performance.Recently,considerable efforts have been devoted to this endeavor.This review systematically summarizes the impact of built-in electric fields on enhancing charge separation and transfer mechanisms,focusing on the modulation of built-in electric fields in terms of depth and orderliness.First,mechanisms and tuning strategies for built-in electric fields are explored.Then,the state-of-the-art works regarding built-in electric fields for modulating charge separation and transfer are summarized and categorized according to surface and interface depth.Finally,current strategies for constructing bulk built-in electric fields in photoelectrodes are explored,and insights into future developments for enhancing charge separation and transfer in high-performance photoelectrochemical applications are provided.

In Situ-Constructed Li_(x)MoS_(2)with Highly Exposed Interface Boosting High-Loading and Long-Life Cathode for All-Solid-State Li-S Batteries

As the persistent concerns regarding sluggish reaction kinetics and insufficient conductivities of sulfur cathodes in all-solid-state Li-S batteries(ASSLSBs),numerous carbon additives and solid-state electrolytes(SSEs)have been incorporated into the cathode to facilitate ion/electron pathways around sulfur.However,this has resulted in a reduced capacity and decomposition of SSEs.Therefore,it is worth exploring neotype sulfur hosts with electronic/ionic conductivity in the cathode.Herein,we present a hybrid cathode composed of few-layered S/MoS_(2)/C nanosheets(<5 layers)that exhibits high-loading and long-life performance without the need of additional carbon additives in advanced ASSLSBs.The multifunctional MoS_(2)/C host exposes the abundant surface for intimate contacting sites,in situ-formed LixMoS_(2)during discharging as mixed ion/electron conductive network improves the S/Li2S conversion,and contributes extra capacity for the part of active materials.With a high active material content(S+MoS_(2)/C)of 60 wt%in the S/MoS_(2)/C/Li_(6)PS_(5)Cl cathode composite(the carbon content is only~3.97 wt%),the S/MoS_(2)/C electrode delivers excellent electrochemical performance,with a high reversible discharge capacity of 980.3 mAh g^(-1)(588.2 mAh g^(-1)based on the whole cathode weight)after 100 cycles at 100 mA g^(-1).The stable cycling performance is observed over 3500 cycles with a Coulombic efficiency of 98.5%at 600 mA g^(-1),while a high areal capacity of 10.4 mAh cm^(-2)is achieved with active material loading of 12.8 mg cm^(-2).

Construction interlayer structure of hydrated vanadium oxides with tunable P-band center of oxygen towards enhanced aqueous Zn-ion batteries

Layered materials with adjustable framework,as the most potential cathode materials for aqueous rechargeable zinc ion batterie,have high capacity,permit of rapid ion diffusion,and charge transfer channels.Previous studies have widely investigated their preparation and storage mechanism,but the intrinsic relationship between the structural design of layered cathode materials and electrochemical performance has not been well established.In this work,based on the first principles calculations and experiments,a crucial strategy of pre-intercalated metalions in vanadium oxide interlayer with administrable p-band center(ε_(p))of O is explored to enhance Zn^(2+)storage.This regulation of the degree of covalent bond and the average charge of O atoms varies the binding energy between Zn^(2+)and O,thus affecting the intercalation/de-intercalation of Zn2þ.The present study demonstrates thatεp of O can be used as an important indicator to boost Zn2þstorage,which provides a new concept toward the controlled design and application of layered materials.

Tungsten carbide-reduced graphene oxide intercalation compound as co-catalyst for methanol oxidation

Highly dispersed tungsten carbide（WC） nanoparticles（NPs） sandwiched between few-layer reduced graphene oxide（RGO） have been successfully synthesized by using thiourea as an anchoring and inducing reagent.The metatungstate ion,[H2W（12）O（40）]^6-,is assembled on thiourea-modified graphene oxide（GO） by an impregnation method.The WC NPs,with a mean diameter of 1.5 nm,are obtained through a process whereby ammonium metatungstate first turns to WS2,which then forms an intercalation compound with RGO before growing,in situ,to WC NPs.The Pt/WC-RGO electrocatalysts are fabricated by a microwave-assisted method.The intimate contacts between Pt,WC,and RGO are confirmed by X-ray diffraction,scanning electron microscope,transmission electron microscope,and Raman spectroscopy.For methanol oxidation,the Pt/WC-RGO electrocatalyst exhibited an electrochemical surface area value of 246.1 m^2/g Pt and a peak current density of1364.7 mA/mg Pt,which are,respectively,3.66 and 4.77 times greater than those of commercial Pt/C electrocatalyst（67.2 m^2/g Pt,286.0 mA/mg Pt）.The excellent CO-poisoning resistance and long-term stability of the electrocatalyst are also evidenced by CO stripping,chronoamperometry,and accelerated durability testing.Because Pt/WC-RGO has higher catalytic activity compared with that of commercial Pt/C,as a result of its intercalated structure and synergistic effect,less Pt will be required for the same performance,which in turn will reduce the cost of the fuel cell.The present method is facile,efficient,and scalable for mass production of the nanomaterials.

Electrochemical investigation on kinetics of potassium intercalating into graphite in KF melt

The kinetics of potassium intercalating into graphite in molten KF at 1 163 K was investigated by means of cyclic voltammetry and chronoamperometry.Cyclic voltammetry results indicate that intercalaltion/deintercalation of potassium into/from graphite involve kinetic limitations.The intercalation process of potassium was further confirmed to be governed by both the diffusion of potassium ion in graphite bulk and the phase transition kinetics through the analyses of current-time transient curves with reversible and quasi-reversible equations.The transfer coefficient of the intercalation reaction was calculated to be 0.364 according to the parameters resulting from nonlinear fitting of the current-time transient curves with a quasi-reversible equation.Analysis with scanning electron microscope shows that graphite matrix was severely eroded by intercalation of potassium.

A review on anode materials for lithium/sodium-ion batteries

Since lithium-ion batteries(LIBs) have been substantially researched in recent years, they now possess exceptional energy and power densities, making them the most suited energy storage technology for use in developed and developing industries like stationary storage and electric cars, etc. Concerns about the cost and availability of lithium have prompted research into alternatives, such as sodium-ion batteries(SIBs), which use sodium instead of lithium as the charge carrier. This is especially relevant for stationary applications, where the size and weight of battery are less important. The working efficiency and capacity of these batteries are mainly dependent on the anode, cathode, and electrolyte. The anode,which is one of these components, is by far the most important part of the rechargeable battery.Because of its characteristics and its structure, the anode has a tremendous impact on the overall performance of the battery as a whole. Keeping the above in view, in this review we critically reviewed the different types of anodes and their performances studied to date in LIBs and SIBs. The review article is divided into three main sections, namely:(i) intercalation reaction-based anode materials;(ii) alloying reaction-based anode materials;and(iii) conversion reaction-based anode materials, which are further classified into a number of subsections based on the type of material used. In each main section, we have discussed the merits and challenges faced by their particular system. Afterward, a brief summary of the review has been discussed. Finally, the road ahead for better application of Li/Na-ion batteries is discussed, which seems to mainly depend on exploring the innovative materials as anode and on the inoperando characterization of the existing materials for making them more capable in terms of application in rechargeable batteries.

Preparation and Properties of Phenolic Resin/Montmorillonite Intercalation Nanocomposites

Phenolic resin/montmorillonite intercalation composites were prepared by using the methods of pressing intercalation and melt intercalation.Properties and structure of the composites were investigated by using XRD,TG and test of softening point.It is indicated that both the pressing intercalation and melt intercalation can be used to prepare the phenolic resin/organo-montmorillonite intercalation nanocomposites.Compared with phenolic resin,the intercalation nanocomposites have better heat-resistance,higher decomposition temperatures and less thermal weight-loss.However,these two intercalation methods have different effects on the softening point of the intercalation nanocomposites.Pressing intercalation almost does not affect the softening point of the intercalation nanocomposites,while melt intercalation significantly increases the softening point of the intercalation nanocomposites, probably due to the chemical actions happening in the process of melt intercalation.

There is plenty of space in the MXene layers: The confinement and fillings

MXenes have emerged as a new kind of 2D transition metal carbides,nitrides and carbonitrides.Origined from the unique 2D structure with a luxuriant combination of elements,MXenes drive a series of the investigations related to energy storage and conversion,biometrics and sensing,lighting,purification and separation.For 2D layered MXene materials,the interspacing confined by the independent MXenes layers affords a distinct confinement space,which is similar to a nanoreactor that can be utilized for the storage of ions,nanoparticles,nanowires,and the materials with 2D or 3D structure.These fillings confined by MXene layers afford new opptunities for achieving improved properties and performance via complementary natural features,further the synergistic effect.Herein,we summarize the recent reports concerning with the confinded MXenes spacing and the fillings.The modification of interlayer distance lead by the intercalants were explored.We expect that our review may offer the route for a series of ongoing studies to address the MXenes.

STUDY ON INTERCALATION MECHANISM OF GELATIN/MMT NANOCOMPOSITE

A gelatin/MMT nanocomposite was prepared in an aqueous solution and investigated by XRD,FTIR and 13 C NMR,and then the intercalation mechanism was discussed.The result of XRD indicated that the gelatin molecule had already inserted into the interlayer of MMT,and the intercalation or exfoliation structure had been achieved.The result of 13 C NMR demonstrated that the ions interaction between gelatin and MMT was attributed to the driving force for intercalation.In order to confirm the role of -COO - of gelatin in the combination with MMT,lauric sodium was brought in as a model to react with MMT,and was characterized by XRD and FTIR,the result proved that there existed a kind of strong interaction between -COO - and ions of MMT.

Physical Blocking Neural Tube Closure Affects Radial Intercalation and Neural Crest Midline-directed Migration in Xenopus Dorsal Explants

Neural tube defects （NTDs） are severe congenital malformation diseases, which occur in 1 out of 1000 births in human. In Xenopus, several tissue movements are involved in the neural tube closure process. Immediately after the neural tube fusion, the neural crest cells get monopolar protrusion toward dorsal midline and migrate to form the roof of the neural tube. At the same time, radial intercalation takes place from the ventral neural tube and forces it to be single-layered. Here, we physically block the neural tube closure to test the cell movements and the following patterning in Xenopus laevis explants. The results show that the single-layered neural tube fails to form and the neural crest cells remain at the lateral regions in the explants with NTDs. However, the patterning of the neural tube is not affected as indicated by the normal expression of the preneural genes. These results indicate a requirement of the neural tube fusion for the radial intercalation and the dorsal midline directed neural crest migration, but not for the dorsal-ventral patterning of the neural tube.

Lithium intercalation/de-intercalation behavior of a composite Sn/C thin film fabricated by magnetron sputtering

A tin film of 320 nm in thickness on Cu foil and its composite film with graphite of-50 nm in thickness on it were fabricated by magnetron sputtering. The surface morphology, composition, surface distributions of alloy elements, and lithium intercalation/de-intercalation behaviors of the fabricated films were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, electron probe microanalyzer （EPMA）, X-ray photoelectron spectroscopy （XPS）, inductively coupled plasma atomic emission spectrometry （ICP）, cyclic voltammetry （CV）, and galvanostatic charge/discharge （GC） measurements. It is found that the lithium intercalation/de-intercalation behavior of the Sn film can be significantly improved by its composite with graphite. With cycling, the discharge capacity of the Sn film without composite changes from 570 mAh/g of the 2nd cycle to 270 mAh/g of the 20th cycle, and its efficiency for the discharge and charge is between 90% and 95%. Nevertheless, the discharge capacity of the composite Sn/C film changes from 575 mAh/g of the 2nd cycle to 515 mAh/g of the 20th cycle, and its efficiency for the discharge and charge is between 95% and 100%. The performance improvement of tin by its composite with graphite is ascribed to the retardation of the bulk tin cracking from volume change during lithium intercalation and de-intercalation, which leads to the pulverization of tin.

Intercalation Assembly Method and Intercalation Process Control of Layered Intercalated Functional Materials

Layered intercalated functional materials of layered double hydroxide type are an important class of functional materials developed in recent years. Based on long term studies on these materials in the State Key Laboratory of Chemical Resource Engineering in Beiiing University of Chemical Technology, the orinciole for the design of controlled intercalation processes in the light of tuture production processing requirements has been developed. Intercalation assembly methods and technologies have been invented to control the intercalation process for preparing layered intercalated materials with various structures and functions.

K+alkalization promoted Ca2+intercalation in V2CTx MXene for enhanced Li storage

Although MXenes is highly attractive as anode materials of lithium ion batteries,it sets a bottleneck for higher capacity of the V2CTxMXene due to the limited interlayer space and the derived surface terminations.Herein,the cation intercalation and ion-exchange were well employed to achieve a K+and Ca2+intercalated V2CTxMXene.A larger interlayer distance and low F surface terminations were thereof obtained,which accelerates the ion transport and promotes the delicate surface of V2CTx MXene.As a result,a package of enhanced capacity,rate performance and cyclability can be achieved.Furthermore,the ion exchange approach can be extended to other 2 D layered materials,and both the interlayer control and the surface modification will be achieved.

Spectroscopy Study on Crystal Structure of Ce(NO_3)_3(phen)_2 and Interactions of Ce(NO_3)_3(phen)_2 with DNA

The absorption, fluorescence and Raman spectra of Ce(NO3)(3)(phen)(2) complex were assigned and the crystal structure of the complex was studied. Meanwhile the interactions between Cc (NO3)(3) (phen)(2) and DNA were studied by spectrum methods. As DNA was added, it is found that both the UV absorption bands of Ce(NO3)(3)(phen)(2) and the SERS bands of Ce(NO3)(3)(phen)(2) weaken evidently, while the fluorescence intensity of Ce(NO3)(3)(phen)(2) enhance dramatically. The complex compete against EB on the reaction with DNA. It is indicated by this spectrum methods that there are strong interactions between Ce(NO3)(3)(phen)(2) and DNA, and the bond mode is intercalation. The bond constant of the complex with DNA is determined to be 1.7 x 10(5).

Influence of blasting on the properties of weak intercalation of a layered rock slope

A precondition for correctly analyzing the stability of a slope and designing its bracing structure is to study and determine the influence of excavation blasting on the properties of weak intercalation in the layered rock slope. On the basis of in-situ stratification-cracking blasting tests, the properties of weak intercalation were investigated using the LS-DYNA3D program. The displacement distribution and compactness of weak intercalation at different positions away from the charge center and their various laws are discussed. The critical displacement of stratification-cracking （0.1 mm） was obtained, and an approximate expression of compactness were deduced. Furthermore, through the simulation of a layered rock blasting under the same geological conditions, the stratification-cracking effect of deep-hole blasting on the properties of weak intercalation was compared with that of short-hole blasting, and the influencing differences, in addition to their causes, were analyzed. The results indicated that the blasting cavity of weak intercalation in short-hole blasting with a radius of 40 mm was nearly a circle, whose radius was about 28.7 cm; whereas in deep-hole blasting with a radius of 150 mm, the shape of the blasting cavity was different from that in short-hole blasting, the radius of the cavity behind the charge （89.1 cm） was further smaller than those of the other three （138.7 cm）, and there were sharp crinkles on the surface of weak intercalation. When the distance from the charge center （DCC） was less than 40 and 150 cm in short-hole and deep-hole blasting, respectively, the displacement of weak intercalation was reduced remarkably with the increase in DCC.